Induction heating coil



Oct. 26, 1948.- R. J. STANTON ETAL INDUCTION HEATING 0011.

Filed Sept. 6, 1945 mv ENT'OFZS Pose/2T J 5 TA/vTo/v CHRISTOPHER LOVYFZY7W GW MM? AT TO RN EYS Patented Oct. 26, 1948 UNITED STATES PATENTOFFICE INDUCTION HEATING COIL of New York Application September 6, 1945,Serial No. 614,688

1 Glaim. 1

This invention pertains to an induction heating coil of novelconstruction, particularly adapted for use in uniformly hardening theface portions of internal combustion engine rocker arms and other metalobjects of analogous configuration.

Owing to the peculiar shape of internal combustion engine rocker armsand the like, extreme difficulty has been encountered in devising meansfor so heating the face portions thereof by means of high frequencyinduced currents, as to provide a uniform hardness pattern over the faceportion on subsequent quenching. The present invention provides a highfrequency induction coil construction which is ideally adapted to suchpurposes.

In accordance with its preferred embodiment, the coil of the presentinvention consists of a single tubular conductor, composed of a metal,such as copper, having relatively high heat conductivity and low highfrequency losses, this conductor being formed into a series of spacedconvolutions, a portion of the turns of which are disposed substantiallyparallel to one plane while the remaining turns are disposedsubstantially parallel to a second plane intersecting the first, wherebythe two coil portions form in effect a dihedral angle adapted to receivetherein the face portion of the object to be hardened, such as aninternal combustion engine rocker arm, the portions of the tubularconductor which form the apex of the dihedral angle being preferablyspaced with substantial uniformity across the face of the object when soinserted, for purposes of uniformly and efiiciently heating the same.The terminals of the so-wound tubular conductor are connected tosuitable electrical conductors for applying a source of high frequencyenergizing voltage thereto; and also are provided with suitable pipeextensions for circulating a cooling liquid, such as cold water, throughthe coil during the heating operation.

In the annexed drawing:

Fig. l is a plan view of a coil assembly in accordance with theinvention, provided with suitable electrical connections for energizingthe coil from a. high frequency source, and provided also with theaforesaid pipe extensions for circulating the cooling liquid through thecoil during heating. This View also includes a showing of an internalcombustion engine rocker arm as disposed in proper relation to the coilfor uniformly heating the face portion thereof.

Fig. 2 is a partial side elevation of the Fig. 1 showing, illustratingparticularly the arrange-.

ment of the rocker arm in relation to the coil for the uniform heatingaforesaid.

Fig. 3 is a section at 33 of Fig. 2 looking to the right therein; whileFig. 4 is a section at 4-4 of Fig. 2 looking to the left therein.

Fig. 5 is a plan view of the heating coil, corresponding to the showingthereof in Fig. 1, but with the rocker arm removed, to illustrate thecoil construction more in detail.

Referring to the various figures of the drawing, in which like elementsare similarly designated, the high frequency induction coil of theinvention, shown generally at l, comprises, as stated, a single piece ofmetal tubing 2, Fig. 4, of copper or the like, formed into a series ofspaced convolutions, such as 3, 4, 5, 6, a portion, preferably half, ofthe turns of which, such as 3, 4, are arranged substantially parallel toone plane, while the remaining convolutions, such as 5, 6, are ar angedsubstantially parallel to a second plane intersecting the first, to formin effect a dihedral angle therebetween, as indicated at I, Fig. 3. Thisangle is of such aperture as to permit the insertion therein of theportion 8, to be facehardened, of an internal combustion engine rockerarm 9 or the like.

In order to assure substantially uniform heating across the entire faceof the portion 8 to be hardened, the portions ID to i3, Fig. 3, of thetubular conductor forming the apex of the dihedral angle 1, arepreferably spaced with substantial uniformity in parallel relation andin a common plane, as shown, whereby all portions of the face 8 aresubjected to approximately the same flux density, whereby all portionsof the face are heated with relative uniformity throughout, so that onsubsequent quenching to harden, an even hardness pattern is obtainedover the entire rocker arm face.

Since it is desired to impart maximum hardmess to only the face portion8 of the rocker arm, leaving the balance relatively tough andunhardened, for purposes of withstanding shock, etc., the coilconvolutions 3 to 6 inc. are flared progressively outwardly away fromthe rocker arm face portion as shown at l4, l5, Fig. 1, thereby tominimize heating of the rocker arm, except for the face portion 8.

The coil l is brazed at its terminals [6, IT to the pipe extensions l8,l9, which extend through conductive sleeves 20, 2| of copper or thelike, to other pipe extensions, such as 22, 23, the latter extending toa source of supply for circulating cold water or the like through thecoil l during operation. The conductive sleeves 20, 2| terminate inright-angle lugs, such as 24, 25, the latter being brazed to conductiveconnecting lugs 28, 27 secured in position on a high frequency supplytransformer '28 by the transformer bushings 29, 30. An insulating panel31 through which the copper sleeves 20, 2| extend, is mounted in frontof the transformer 28 to protect the operator from the high frequencytransformer voltage. During the heating operation, the rocker arm 9 orthe like is supported, as shown in Fig. 1, on a cylindrical stud 32carried by a supporting table 33.

From the aforesaid description of the invention as applied specificallyto the face hardening of internal combustion engine rocker arms,its'application to the face hardening of various other objects will beapparent; as will also its application to various other high frequencyinduction heat treatments, such as annealing, tempering, brazing,soldering, etc.

We claim:

An induction heating coil comprising a length of tubular conductor woundin a plurality of generally helical spaced convolutions of approximatelythe same dimensions, said convolutions merging into one another insuccession continuously from one end of the conductor to the other, aplurality of such convolutions being arranged substantially parallel toa first plane, another plurality thereof being arranged substantiallyparallel to a second plane intersecting the first and forming thereby adihedral angle adapted to receive therein a portion of an object to beheat treated, said convolutions all having substantially straightportions disposed in substantially parallel positions along a thirdplane which is parallel to the line of intersection of said first andsecond planes, at least four of such parallel portions thus beingprovided along said third plane for generally conforming to a surfaceportion of said object to be heated, the remaining portions of theconvolutions diverging from said plane at either side along said firstand second planes, and a pair of high frequency energizing terminalsconnected respectively to the ends of saidconductor at the first andlast of the successive convolutions.

ROBERT J. STANTON.

CHRISTOPHER LOWRY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number -Name. Date 2,052,010 Bailey Aug. 25-, 19362,075,079 Anderson Mar. 30,. 1937 2,320,573 Doelker June 1, 1943 OTHERREFERENCES

